There is a clear need in the dental profession for an inexpensive and effective means for the cosmetic treatment of discolored teeth. Discoloration can result from many different causes, such as nicotine staining, excessive ingestion of fluoride, reaction to tetracycline and similar pharmaceutical products, trauma, root canal therapy, and various systemic disorders.
Discolored teeth are treated by dentists in a number of different ways short of extraction. Bleaching has been tried, but the results are unpredictable. Sometimes it doesn't help at all, and in any case, it is difficult to control the final color of bleached teeth. Crowns ("capping") have also been used. But crowns are quite expensive and require considerable grinding away of the tooth. Further, they are usually contraindicated with children.
Polymerizable dental composite materials have been used to treat discolored teeth in the following manner:
Peroxide-cured, filled polymeric materials are shaped by placement in the anterior portion of a plastic crown former, which acts as a mold. The material is then applied to the tooth, using a layer of unfilled bonding agent as a "primer coat" on the tooth. After the material has hardened, it must be polished. Cured resin-filled, composite polymeric materials have been used in a similar manner, except that the crown former was not used as a mold. But the dentist still had to shape it by hand and polish the veneer. (See Spencer, J. Dent. Child, 39, pp. 443-446, November-December, 1972.)
Preformed veneers can also be used. They are applied by using unfilled bonding agents to adhere the veneer to the tooth and filled composites to "feather" the corners.
None of the above-discussed known procedures for treating discolored teeth is fully satisfactory. Crowns are expensive; bleaching is unpredictable; the use of polymeric composites requires an awkward procedure; and preformed veneers are bulky, require time-consuming and complicated procedures to install, tend to leak around the margins, and can't be shaded.
The present invention provides a relatively inexpensive and effective means for treating discolored teeth.